AD 96-01-04 R1

This amendment revises an existing airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that currently requires revising the Airplane Flight Manual (AFM) to require verification that the auto-ignition system is operational; to define icing conditions at higher ambient temperatures; and to provide the flight crew with limitations and procedures to aid in the avoidance of engine power interruptions. The actions specified by that AD are intended to prevent failure of the auto-ignition system to re-light the engine in the event of power interruptions due to the ingestion of ice and/or slush into the engine, which could result in engine flameout and subsequent shutdown, and to provide the flight crew with guidance to aid in avoidance of such occurrences. This amendment clarifies certain requirements of the AFM revision. This amendment is prompted by communications received from affected operators that certain of the currentrequirements of the AD are unclear.

Final rule; request for comments

96-01-04 R1 SAAB AIRCRAFT AB: Amendment 39-9582. Docket 96-NM-74-AD. Revises AD 96-01-04, Amendment 39-9480.
Applicability: Model SAAB SF340A series airplanes, serial numbers 004 through 159 inclusive; and Model SAAB 340B series airplanes, serial numbers 160 and subsequent; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the auto-ignition system to re-light the engine in the event of power interruptions due to the ingestion of ice and/or slush into the engine, which could result in engine flameout and subsequent shutdown; and to provide the flight crew with guidance to aid in avoidance of such occurrences; accomplish the following:

(a) Within 10 days after the effective date of this AD, revise the FAA-approved Airplane Flight Manual (AFM) to include the text contained in paragraphs (a)(1), (a)(2), (a)(3), and (a)(4) of this AD, as applicable. This may be accomplished by inserting a copy of this AD into the AFM.

(1) For Model SAAB SF340A series airplanes: Insert the following sub-section in the Limitations Section of the AFM:

"IGNITION SYSTEM

Prior to each engine start, perform a check of the auto-ignition system.

o Select batteries ON (external power ON or OFF).

o Check that IGN switches are in NORM position.

o Advance PLs above FLT IDLE and verify the IGN lights in the Flight Status Panel (FSP) illuminate. In bright sunlight, shade FSP to ensure IGN lights are visible when illuminated.

o Retard PLs to GND IDLE. (IGN lights should go out.)

o If an IGN light fails to illuminate when PLs are above FLT IDLE, the auto-ignition system is considered to be inoperative.

If the auto-ignition system is inoperative:

o BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT. Maintain ignition in CONT until touchdown, even if icing conditions cease to exist.

o The obligation to comply with the current version of the Master Minimum Equipment List (MMEL), Revision 11, or later approved revisions is not affected by this limitation."

(2) For Model SAAB 340B series airplanes: Insert the following sub-section in the Limitations Section of the AFM:

"IGNITION SYSTEM

During each engine shutdown, perform a check of the auto-ignition system.

o Adjust Ng to approximately 75%-77%; minimum is 75%.

o Shut down the engines (CL to FUEL OFF).

o Verify the IGN lights in the Flight Status Panel (FSP) illuminate while Ng is above 62%. In bright sunlight, shade the FSP to ensure that lights are visible when illuminated.

o If an IGN light fails to illuminate, the auto-ignition system is considered to be inoperative.

o Retard PLs to GND IDLE.

If the auto-ignition system is inoperative:

o BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT. Maintain ignition in CONT until touchdown, even if icing conditions cease to exist."

o The obligation to comply with the current version of the Master Minimum Equipment List (MMEL), Revision 11, or later approved revisions is not affected by this limitation.

(3) For all airplanes: Insert the following in the Limitations Section of the AFM, under Icing Conditions:

"For engine anti-ice system activation, icing conditions exist when visible moisture in any
form is present (such as clouds, fog with visibility of one mile or less, rain, snow, sleet, ice
crystals) or standing water, slush, or snow (hard packed snow excluded) is present on the
ramps, taxiways, or runways and the OAT or SAT is +10 degrees C and below during
ground and flight operation.

For all airplane operations other than engine anti-ice, icing conditions exist when visible
moisture in any form is present (such as clouds, fog with visibility of one mile or less, rain,
snow, sleet, ice crystals) or standing water, slush, or snow (hard packed snow excluded)
is present on the ramps, taxiways or runways and the OAT or SAT is +5 degrees C and
below during ground and flight operation."

(4) For all airplanes: Insert the following in the Normal Procedures Section of the AFM, under Operation in Icing Conditions:

"CAUTION

Engine power interruptions may occur atISA to ISA +20 degrees Celsius temperature and
in light (or undetected) icing conditions, or shortly after exiting these conditions. Engine
function will normally be recovered by the auto-ignition system before any serious loss of
power. To aid in avoidance of these occurrences:

o Engine anti-ice systems must be activated prior to entering icing conditions, and
maintained ON for at least 5 minutes after exiting icing conditions."

(b) For Model SAAB 340B series airplanes: If an auto-ignition system is found to be inoperative, prior to further flight, perform an Np overspeed test to ensure that the Np overspeed system is operative, in accordance with the procedures specified in General Electric Maintenance Manual SEI-576. If the Np overspeed system is found to be inoperative, prior to further flight, repair in accordance with the procedures specified in General Electric Maintenance Manual SEI-576.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) This amendment becomes effective on May 10, 1996.

On January 2, 1996, the FAA issued airworthiness directive (AD) 96-01-04, amendment 39-9480 (61 FR 511, January 8, 1996), which is applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes. That AD requires revising the FAA-approved Airplane Flight Manual (AFM) to:

1. require verification that the auto-ignition system is operational;

2. define icing conditions at higher ambient temperatures; and

3. provide the flight crew with limitations and procedures to aid in the avoidance of engine power interruptions.

That AD action was prompted by a report of complete power loss of the left engine and power fluctuations on the right engine as a result of build up of ice and/or slush in the engine inlet and subsequent ingestion into the engines. The actions required by that AD are intended to prevent failure of the auto-ignition system to re-light the engine in the event of power interruptions due to the ingestion of ice and/orslush into the engine, which could result in engine flameout and subsequent shutdown, and to provide the flight crew with guidance to aid in avoidance of such occurrences.

Since the issuance of that AD, the FAA has received communications from the Swedish airworthiness authority, Luftfartsverket (LFV), and various affected operators indicating that certain text of the AFM revision as cited in AD 96-01-04 is not clear.

Request to Clarify Frequency of Checks
Affected operators specifically request that the frequency of the auto-ignition system checks, as specified in the AFM revision contained in paragraphs (a)(1) and (a)(2) of AD 96-01-04, be clarified. As AD 96-01-04 was worded, some operators may have misinterpreted its requirements to mean that the engine must be shut down following each flight and restarted before the next flight.

The FAA finds that clarification is necessary to prevent such misinterpretation. The FAA did not intend that the AD require shutdown of theengine following each flight. The FAA acknowledges that some operators may elect not to shut down the engine following each flight. In such a case, this AD does not require that a check of the auto-ignition system be performed. Therefore, the FAA has determined that the limitations specified in paragraph (a)(1) and (a)(2) of AD 96-01-04 must be revised to clarify that the check of the auto-ignition system is required prior to each engine start and during each engine shutdown.

Request to Clarify Relationship of AD to MMEL
The LFV noted that the AFM revision specified in paragraphs (a)(1) and (a)(2) of AD 96-01-04 may imply that dispatch may occur indefinitely with an inoperative auto-ignition system.

The FAA finds that clarification of this point is necessary. The intent of AD 96-01-04 was that, if the auto-ignition system is found to be inoperative, dispatch should be accomplished in accordance with the Minimum Master Equipment List (MMEL). The FAA finds that the additionof that information to the AFM revision specified in paragraphs (a)(1) and (a)(2) of this AD will clarify the dispatch requirements.

Request to Clarify Definition of "Icing Conditions"
For systems other than engine anti-ice activation, affected operators request that a separate and relieving definition of "Icing Conditions" of Outside Air Temperature (OAT) or Static Air Temperature (SAT) be included in paragraph (a)(3) of the AD, with the OAT or SAT criteria to be specified as +5 degrees Centigrade (C).

The FAA agrees that the definition of "Icing Conditions" needs to be clarified for systems other than engine anti-ice. The FAA finds that paragraph (a)(3) of the AD must be revised to expand the definition of "Icing Conditions" by including a separate definition for all airplane operations other than engine anti-ice, which specifies the OAT or SAT criteria as +5 degrees C.

Conclusion
Based on the issues raised by the affected operators and the LFV, the FAA finds that AD 96-01-04 must be revised as discussed previously. These revisions will ensure that the requirements of the AD are understood clearly. Clearer understanding will ensure that the intent of the AD is met and that the addressed unsafe condition is prevented.

Explanation of the Revised Rule
This airplane model is manufactured in Sweden and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement.

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD revises AD 96-01-04 to continue to require verification that the auto-ignition system is operational; to define icing conditions at higher ambient temperatures for engine anti-ice systems; and to provide the flight crew with limitations and procedures to aid in the avoidance of engine powerinterruptions. For Model SAAB 340B series airplanes having an auto-ignition system that is found to be inoperative, this AD also continues to require a test of the Np overspeed system to ensure that it is operative, and repair, if necessary.

In addition, this AD revises the AFM revision by:

1. clarifying the times at which the auto-ignition checks are to be performed;

2. specifying that the dispatch with the auto-ignition system inoperative shall be done in accordance with the current MMEL; and

3. providing a relieving definition of Icing Conditions for systems other than engine anti-ice.

This is to be considered interim action until final action is identified, at which time the FAA may consider further rulemaking.

Effective Date of the Revised Rule
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-NM-74-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, itis determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by removing amendment 39-9480 (61 FR 511, January 8, 1996), and by adding a new airworthiness directive (AD), amendment 39-9582, to read as follows: